The past several years have seen the emergence of a new industry, the so called "jeans stonewashing" segment, generated by the fashion demands of a generation desirous of stylish, but informal and comfortable clothing.
Originally, all of the indigo jeans on the market were stiff and uncomfortable when first purchased, due to the finishing system used for denim fabrics.
The first step in the processing evolution was to sell jeans that had been laundered by the manufacturer. These "pre-washed" jeans had a slightly faded appearance and a softer hand that felt comfortable, as though they had been laundered several times. This trend became fashionable as well, and consumers were willing to pay the extra cost involved for this additional processing.
Not long after the introduction of pre-washed jeans, the idea of using abrasive stones to accelerate the aging process was developed, and "stone washing" became the second step in the evolution. Volcanic stones were included in the wash, or tumbled with the damp garments to wear down the stiffest portions such as belt areas, cuffs, and pockets.
However, the use of stones to abrade jeans is very destructive to equipment and fabric, so today the stones are often substituted with a cellulase treatment, or a combination of stones and cellulase is used to achieve the abraded (worn) look; for reference see "AATCC: Garment Wet Processing Technical Manual", 1994, published by American Association of Textile Chemists and Colorists, pp. 19-21.
The fabric looses strength by using the stone-process described above, and the stone-free cellulase treatment does not alone give the desired worn look, so there is a need in industry for a more gentle process.